522 MANUAL OF ZOOLOGY. 



large, longer than the head, and sometimes of comparatively 

 gigantic size. The mandibles are, however, to a very great 

 extent hollowed out into air-cells, so that the weight of the bill 

 is much less than would be anticipated from its size. The 

 tongue is very long, notched at its side, or feathered with deli- 

 cate lateral processes. The Toucans live chiefly upon fruits. 

 and are all confined to the hotter regions of South America, 

 frequenting the forests in considerable flocks. 



The Trogons have short and weak feet, a short triangular 

 bill, the gape bordered with strong bristles, and short wings. 

 The plumage is soft and loose, and generally of the most gor- 

 geous description. They inhabit the most retired recesses of 

 the forests of the intertropical regions of both hemispheres, 

 and show many decided points of affinity to the Goat-suckers. 



ORDER VI. INSESSORES. The sixth order of Birds is that of 

 the Inses sores, or Perchers often spoken of as the Passer es, or 

 " Passerine" Birds. They are defined by Owen as follows : 

 " Legs slender, short, with three toes before and one behind, 

 the two external toes united by a very short membrane" (fig. 

 227, A, B). 



"The Perchers form the largest and by far the most nume- 

 rous order of birds, but are the least easily recognisable by dis- 

 tinctive characters common to the whole group. Their feet, 

 being more especially adapted to the delicate labours of nidi- 

 fication, have neither the webbed structure of those of the 

 Swimmers, nor the robust strength and destructive talons which 

 characterise the feet of the Birds of Rapine, nor yet the ex- 

 tended toes which enable the Wader to walk safely over 

 marshy soils and tread lightly on the floating leaves of aquatic 

 plants; but the toes are slender, flexible, and moderately 

 elongated, with long, pointed, and slightly-curved claws. 



" The Perchers in general have the females smaller and less 

 brilliantly coloured than the males ; they always live in pairs, 

 build in trees, and display the greatest art in the construction 

 of their nests. The young are excluded in a blind and naked 

 state, and wholly dependent for subsistence during a certain 

 period on parental care. The brain arrives in this order at its 

 greatest proportionate size ; the organ of voice here attains its 

 greatest complexity, and all the characteristics of the bird, as 

 power of flight, melody of voice, and beauty of plumage, are 

 enjoyed in the highest perfection by one or other of the groups 

 of this extensive and varied order." 



The structure of the feet, then, gives the definition of the 

 order, but the minor subdivisions are founded on the nature 

 of the beak ; this organ varying in form according to the 



